Geospatial variability in the egg raft distribution and abundance of Culex pipiens and Culex restuans in Urbana-Champaign, Illinois

The aim of this study was to determine whether areas of high Culex pipiens and Culex restuans abundance in an urban environment, based on fixed oviposition surveillance sites, corresponded to remotely sensed data. A land use land cover (LULC) classification, based on Landsat-7 Enhanced Thematic Mapper Plus (ETM+) data acquired in July 2003 and Landsat-5 TM data from July 1991, was compared to the abundance of Culex egg rafts in Urbana-Champaign, East-Central Illinois. We performed a maximum likelihood, unsupervised classification and generated three land cover classifications: urban, non-urban and water. Ground coordinates of the Culex surveillance sites were overlaid onto LULC maps with 10 m² grid cells. The grid was stratified based on levels of drainage: 0=poorly drained and 1=well-drained. Total LULC change from 1991 to 2003 in the Urbana-Champaign study site was relatively low, at 12.1%. The most frequent LULC category was maintained urban. The egg raft rate was significantly higher in urban LULC habitats. Remote stratification of the urban land cover using QuickBird visible and near-infrared (NIR) data revealed that high-density canopy coverage was most frequently associated with high Culex abundance in oviposition traps. We demonstrate that optical remote sensing can identify land use parameters associated with high Culex oviposition.